924Board.org

[Rattlinbone]

Okay, I had my engine rebuilt, and that's neat. It runs pretty well and all, but here's the rub. With just over 500 miles on the rebuilt motor, I'm getting pretty bad gas mileage. I'm talking like under 10 miles per gallon! Aren't these cars supposed to get between 20 and 25 MPG? Could rebuilding an engine cause a drop of fuel efficiency like that? Can you think of anything I could do to improve it's fuel economy?
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Fred- 1979 924

[Rasta Monsta]

Assuming your new motor got new plugs, wires, cap & rotor:

Check system and control pressures, hot and cold (per FSM), set mixture per FSM, verify ignition timing (and dwell?), service injectors and CSV.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[!tom]

Also,

Check for fuel leaks
Check the accuracy of your odometer

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78 924 NA
5-lug

[emoore924]

Ja, something isn't right there. Simple tailpipe emissions test should show huge HC. Do the basics -- spark, fuel, timing. With a variance that large, you'll find it quickly...

[joecitizennn]

Yike! At that rate you should have a very sooty exhaust pipe.
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold

[jazz guy]

Using an exhaust sniffer would be a good step in determining what's going on. As emoore924 suggested, you should have a lot of unburned fuel (HC) showing up. 10mpg is awful mileage for these cars, so the culprit should be relatively easy to track down.

Have you done a compression test to determine if everything has seated internally since your rebuild? If not, that is something I woud check as well. Good luck!

Cheers, Brian
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'81/'81/'82

[Rattlinbone]

Well, I certainly do have a sooty exhaust pipe. And I know it's new soot because it's a new exhaust pipe. So there you go. Since the rebuild, I have not touched the engine, just trying to get 500 miles in it before I started futzing with it. Gonna change the oil this next weekend. I'm fairly sure I'll need to take off the valve cover, check the torque on the bolts and readjust the valves. Check the control pressures, timing, injectors, compression, fuel/air mix and plugs. Once I've got all that done, I'll drive it around for a while and see if there's any improvement. Sound like a plan? Leaving anything out?
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Fred- 1979 924

[joecitizennn]

Yeah, you need to add a turbocharger, intercooler and oil cooler. That should fix it.
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold